1. Field of the Invention
The present invention relates generally to the field of aircraft tracking and information services, and more specifically to a system capable of receiving and processing transmissions from multiple aviation sources, including, but not limited to, automatic dependent surveillance-broadcast (ADS-B) towers, Very High Frequency Omni-Range (VOR) ground stations, and other aircraft.
2. Description of the Related Art
Automatic Dependent Surveillance-Broadcast, or ADS-B, is a surveillance technology for tracking aircraft that is part of the Next Generation (NextGen) Air Transportation System.
The system relies on two avionics components: a high-integrity GPS navigation source and a data link (ADS-B unit or receiver). There are several types of certified ADS-B data links, but the most common ones operate at 1090 MHz, essentially a modified Mode S transponder, or at 978 MHz (United States only).
ADS-B consists of two different services, “ADS-B Out” and “ADS-B In”. “ADS-B Out” periodically broadcasts information about an aircraft, including identification, current position, altitude, and velocity, to the outside world, providing air traffic controllers with real-time position information typically more accurate than the information available with current radar-based systems. “ADS-B In” is the reception by aircraft of information including weather data, flight information, traffic avoidance information, and direct communication from nearby aircraft.
The ADS-B system can provide traffic and government generated graphical weather information through the TIS-B (Traffic Information Services-Broadcast) and FIS-B (Flight Information Services-Broadcast) applications.
The majority of aircraft operating within United States airspace will be required to be equipped with at least “ADS-B Out” by January of 2020. Because of this move toward the mandate of ADS-B equipped aircraft, it is seen as important to aviation electronics suppliers and pilots alike that an inexpensive, yet reliable system be available for implementation of the ADS-B functionality. Some suppliers are offering ADS-B solutions that interface with mobile computing devices such as an iPad, in order to provide a relatively inexpensive display for the system that is also capable of running applications and performing other tasks when not being used as an ADS-B display.
While using a mobile device such as an iPad is an innovative approach, the solution is not without its issues. Mobile devices run on battery power, and therefore often drop into “sleep” mode in order to conserve battery life. When the mobile device is in sleep mode, or when the ADS-B application (that is, the software application or program executing on the mobile device and performing the ADS-B functionality) is pushed into the background by another competing application running on the mobile device, the ADS-B application is likely not receiving broadcasts from the ADS-B system, and therefore may be missing important weather updates. When a pilot or other operator turns the mobile device on (or “wakes” it from sleep mode) to check the weather, he or she may have just missed a weather broadcast, or may have missed one almost 15 minutes earlier (the approximate broadcast rate of national weather updates), and so the weather display may be significantly out of date. The pilot could fly into inclement weather he or she cannot see on the erroneous (not updated) display.
What is needed in the art is a system that is capable of caching multiple generations of broadcast data (including but not limited to ADS-B weather broadcasts), providing access to those multiple generations of data or to a selected subset thereof to a mobile device upon request by the mobile device, a means for displaying the data or data subset on the mobile device either as still imagery or as an animation, and a means for automatically detecting when the mobile device has “awakened” or turned on and transmitting cached broadcast data to the mobile device upon wake up such that it is displayed in a usable manner.